Table of contents

1. Introduction to Biochemistry4h 34m
2. Water3h 23m
3. Amino Acids8h 10m
4. Protein Structure10h 4m
5. Protein Techniques14h 5m
6. Enzymes and Enzyme Kinetics13h 38m
7. Enzyme Inhibition and Regulation 8h 42m
8. Protein Function 9h 41m
9. Carbohydrates7h 49m
10. Lipids5h 49m
11. Biological Membranes and Transport 6h 37m
12. Biosignaling9h 45m
Review 1: Nucleic Acids, Lipids, & Membranes2h 47m
Review 2: Biosignaling, Glycolysis, Gluconeogenesis, & PP-Pathway3h 12m
Review 3: Pyruvate & Fatty Acid Oxidation, Citric Acid Cycle, & Glycogen Metabolism2h 26m
Review 4: Amino Acid Oxidation, Oxidative Phosphorylation, & Photophosphorylation1h 48m

3. Amino Acids

Amino Acid Groups

Biochemistry

3. Amino Acids

Amino Acid Groups

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Multiple Choice

Which of the following functional groups on an amino acid side chain is polar and can become positively charged at physiological pH?

Hydroxyl group (–OH)

Methyl group (–CH$_3$)

Amino group (–NH$_2$)

Carboxyl group (–COOH)

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Verified step by step guidance

Understand the concept of physiological pH: Physiological pH is typically around 7.4, which is slightly basic. At this pH, certain functional groups on amino acid side chains can gain or lose protons, affecting their charge.

Review the properties of the amino group (–NH₂): The amino group is polar and can act as a base. At physiological pH, it can accept a proton (H⁺), becoming positively charged as –NH₃⁺.

Analyze the hydroxyl group (–OH): The hydroxyl group is polar but does not typically gain or lose protons at physiological pH, so it remains neutral.

Evaluate the methyl group (–CH₃): The methyl group is nonpolar and does not interact with protons at physiological pH, so it remains neutral.

Consider the carboxyl group (–COOH): The carboxyl group is polar and typically loses a proton at physiological pH, becoming negatively charged as –COO⁻. It does not become positively charged.